Graphene oxide wrapped magnetic nanoparticles composites induced by SiO2 coating with excellent regenerability
20 September 2020
Revised: 19 November 2020
Accepted: 20 November 2020
Available online: 26 November 2020
Abstract: Graphene oxide (GO) wrapped Fe3O4 nanoparticles were prepared by coating the Fe3O4 nanoparticles (NPs) with SiO2 layer, and then modifying by amino groups, which interact with the GO nanosheets to form covalent bonding. The SiO2 coating layer plays a key role in integrating the magnetic nanoparticles with the GO nanosheets. Effect of the amount of SiO2 on the morphology, structure, adsorption and regenerability of the composites was studied in detail. Results suggest that an appropriate SiO2 layer can effectively induce the GO nanosheets to completely wrap the Fe3O4 NPs, forming a core-shell Fe3O4@SiO2@GO composites where Fe3O4@SiO2 NPs were firmly encapsulated by GO nanosheets. As an adsorbent to remove Pb(II) cations from waste water, the optimized Fe3O4@SiO2@GO sample exhibits a high saturated adsorption capacity of 253 mg•g-1, and the adsorption process is well fitted by Langmuir adsorption model. Notably, it displays an excellent regeneration, maintaining ~90% adsorption capacity for 5 cycles, while other samples decrease their adsorption capacity rapidly. This work could provide a theoretical guidance to improve the regeneration of the GO based adsorbents.